Even though this does sounds like a bug - can you please let us know what a
"ls -al /Volumes/" in the terminal tells you?
I see this too. I'm running Lightroom 4.4 on a Mac running OS X 10.9.4. I think I see 10 or 15 extra empty "Macintosh HD" entries. Here is what I see for "ls -al /Volumes/":
total 24 drwxrwxrwt@ 5 root admin 170 Aug 14 10:35 ./ drwxr-xr-x@ 41 root wheel 1462 Aug 6 09:56 ../ -rw-r--r--@ 1 501 admin 6148 Mar 15 2012 .DS_Store lrwxr-xr-x 1 root admin 1 Aug 6 09:54 Macintosh HD@ -> / drwxrwxrwx 0 root wheel 0 Aug 14 10:21 MobileBackups/
In the meantime, I have upgraded my operating system to 10.9.4 and the problem has disappeared. Although that doesn't seem to explain jblyer's problem.
Also, and I don't know if this is related, before the OS upgrade it would take several seconds for the thumbnails to load in the Import mode. After the upgrade, that problem has disappeared too.
Ok, this can occur if other applications sometime mount excessively due to some logical error.
In your (jbyler) case it doesn't seem to be the case.
Although I'm wondering why it's called Macintosh HD@ and not only Macintosh HD. This shouldn't cause any problems but it would be good to know if this is the name that you have given it.
Oh, sorry, it's just called "Macintosh HD", no "@" symbol. That's just my shell configuration; I have "ls" aliased to "ls -F" and the "@" indicates that "Macintosh HD" is a symbolic link.
Apologies for the confusion!